1. Field of the Invention
The present invention concerns a diagnostic imaging system for generation of a three-dimensional image data set of an examination subject as well as a method for determination of information about the perfusion of an anatomical anomaly in an examination subject. The invention is particularly suitable for use in the treatment of intraluminal pathologies of the gastrointestinal tract and in particular can be used before the removal of polyps in the intestine of a patient to obtain information about the vascular supply (vasculature) of the polyps.
2. Description of the Prior Art
Polyps in the region of the large intestine are a common disorder. These are initially benign but can grow over several years (on average between 5 to 8 years) and, with a very high probability, develop into malignant tumors (known as the adenoma-carcinoma sequence) over time. The larger the polyp, the greater the probability of its degeneration. Given early treatment, the polyp can be removed with a curative approach (thus in a benign state). Polyps normally are removed in a minimally-invasive manner by means of flexible endoscopy and with thermal removal (ablation) methods. For example, the polyps can be severed at an optimal depth by means of a small cutting tool (loop). The bleeding that arises should be stopped by coagulation. During their growth phase, polyps can form quite large venous and/or arterial vessels that are normally not externally visible to the treating endoscopy physician. After the severing of the polyps, blood flows from the severed vessels. Given a diameter of more than 5 mm and in particular in the case of patients with high blood pressure and/or patients who take blood-thinning medication, the bleeding is not stanched by blood clotting at the cutting site. In many cases, the coagulation (for example due to an RF current with an RF loop) is not sufficient. In the short term such bleeding can require a surgical operation with a transection of the hypogastric region. Other than by the use of a double catheter, which can be used only with difficulty via the working channel of an endoscope, the endoscopic physician has no possibility to determine the vascular status of the polyps beforehand (before the severing of the polyps) and to establish whether the severing will have a small, medium or even a high risk. If bleeding occurs upon severing, this is often sudden and requires a quick procedure (intervention).
DE 102 52 852 A1 describes a processing device of a magnetic resonance system that allows a graphical measurement (data acquisition) using already-acquired, corrected MR overview images, wherein the region of the corrected MR overview image is graphically delimited by other regions.
Furthermore, by means of acquired image data sets from imaging systems such as MR or CT systems, the examined regions can be represented virtually post-processing a three-dimensional image data set in order, for example, to represent the anatomy by segmentation of the images. A virtual colonoscopy (large intestine endoscopy) is likewise possible with the acquired three-dimensional image data sets, in which the intestine can be virtually “flown through” and the intestinal walls can be examined for possible pathologies. Such a virtual colonoscopy is described, for example, in “A review of technical advances in virtual colonoscopy” in Medinfo 2001, Netherlands, Vol. 10, Nr. 3, p. 73-79.
EP 0 959 363 B1 describes magnetic resonance arteriography with dynamic intravenous contrast agent injection.
An automatic segmentation of the colon wall is described in “Interactive polyp biopsy based on automatic segmentation of virtual colonoscopy” in BIBE 2004, Proceedings, Fourth IEEE Symposium on Bioinformatics and Bioengineering, 19-21 May 2004, p. 159-166.
Among other things, it is currently a goal to detect as early as possible the existing risks upon removal of a polyp with regard to the bleeding behavior. It can then be decided from the outset which patients can be treated by means of an operation and which by flexible endoscopy.
For this purpose it is desirable to obtain information about the vascularization of the region to be several before the removal of a pathology. Miniaturized Doppler ultrasound endoscopic probes are available, but their use is too complicated to be routine. Among other things, it is known to insert a piezo-probe into the patient via an endoscope, in an attempt to conclude the vascularization of the polyps to be removed from the flow noise in their proximity. This is, however, difficult and error-prone.